The disclosure relates to marine propulsion systems, including engine speed control systems.
A marine engine speed control system maintains engine speed at the operator-selected engine speed. The engine has a throttle controlling engine speed according to throttle position. In response to the operator changing the operator-selected engine speed from a first-selected engine speed to a second-selected engine speed, the engine speed control system begins moving the throttle to attempt to set engine speed at the noted second-selected engine speed, and then maintain engine speed thereat.
It is common for the engine speed control system to include at least one proportional-integral-derivative (PID) controller to maintain engine speed at the operator-selected engine speed. When the operator changes the operator-selected engine speed from a first-selected engine speed to a second-selected engine speed, such change or delta causes the engine speed control system to begin moving the throttle. The amplification gain of the PID controller needs to be large enough to accommodate various deltas, including large deltas, to afford reasonably quick response time. However, large amplification gain (to accommodate a large delta) causes overshoot when attempting to set engine speed at the noted second-selected engine speed in response to the noted change of selected engine speed chosen by the operator. This can cause undesired instability or oscillation until the PID controller moves the throttle back from the overshoot position in attempting to maintain engine speed at the noted second-selected engine speed. An alternative is to limit the amount of amplification gain of the PID controller to minimize overshoot, but this approach suffers from slower response time, particularly for large deltas.
The present disclosure arose during continuing development efforts in the above technology.